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E39 (1997 - 2003) The BMW 5-Series (E39 chassis) was introduced in the United States as a 1997 model year car and lasted until the 2004 when the E60 chassis was released. The United States saw several variations including the 525i, 528i, 530i and 540i. -- View the E39 Wiki

The build date is 07/00....Well today I bought the correct battery, the 2025, installed it, hit the lock button, nothing..got inside the car, tried the sync method, nothing...I really do not want to call the dealer on this one because I really don't want to buy a whole new key

Is this new 2025 battery fully charged? If not, it takes approx 30 hours to fully charge the key...so start using the key while driving around...then try to program it.

Its brand spanking new. I guess I'm gonna call a dealer and find out how much they charge because I know its different prices all over the states. Hopefully I won't have to pay an arm and a leg just to be able to lock the car as I walk away or unlock it as I'm walking to it. But, what exactly do you mean by try to use it? Do you mean try to unlock or lock the doors while its in the ignition?

Oh and on a side note, just found out today that if you have the hood popped but not fully open, and the doors locked, if you try to pop the hood, the alarm will sound. First time I've heard it since I have had the car.

These batteries are definitely rechargeable and if you have one of those oral B rechargeable toothbrushes, simply leave your key positioned in the charging base for a day or two and this should recharge the battery if the battery is still functional. This worked for me on my spare key which I never used for a long time. The charging base of the toothbrush is made entirely of plastic with no conductive metal and charges the toothbrush in the same way as our keys apparently get charged when in the ignition. This may be worth trying before cutting into your key.
Great DIY write-up to the OP and all others.

Hi there, I need some urgent help from you guys.
Can someone with high resolution photo of the key, or can open the key to read the marking on a component which is marked in red arrow in my attached picture.
I accidentally damage it while opening the key for battery replacement and apparently the remote function stops working.
Really appreciate it!
Thank you!

I'm a girl, a proper girly girl - but my husband is a very good hobby mechanic. That said, he's not so good with electrics or electronics.

So I figured - I have a useless diamond key fob and it's going to cost me about £150 to get a new key and fob. What have I got to lose if I bust it open and have a go at the battery? So I bought a new one off ebay for a fiver. In the meantime and encouraged by a glass of wine, I started to cut the cover open with a craft knife. It was slow going, so I went to the kitchen and used a smooth carving knife. It opened easily.

The internal buttons were not working and everything else seemed in tact, so I started trying to detatch the battery from the connectors and they were firmly stuck on. I hacked and hacked. Then I noticed that the conductive thingy (copper wire spiral) was not looking very uniform, some of the copper wires were gapped. So it rubbed them with the back of my nail till they looked even. Et Voila! The internal buttons began to work. I folded the battery and connectors back together, glued the case back together and I have saved myself a small fortune.

WARNING!
What you get with this is that you wont be able to start your car next time your key runs out of battery.
This coil is used to get energy to the rfid that unlocks the electronic blocking system. When you plug in the key, a signal is sent to the key by the car and the key sends a signal back to the car using part of the energy contained in the signal sent by the car. This energy is collected using, correct me if I'm wrong that shame coil you are removing.

WARNING!
What you get with this is that you wont be able to start your car next time your key runs out of battery.
This coil is used to get energy to the rfid that unlocks the electronic blocking system. When you plug in the key, a signal is sent to the key by the car and the key sends a signal back to the car using part of the energy contained in the signal sent by the car. This energy is collected using, correct me if I'm wrong that shame coil you are removing.

That is the induction coil used to keep the rechargeable battery inside the key recharged as well as the facilitating the induction for the EWS transponder chip which is also soldered to the IC board on the new style diamond shaped key.

I tried to replace battery in my E39 key. I checked the old (original) battery and it was showing good voltage. Even then I replaced it with new one. The key remote is still not functional.

When I put the new battery in, I was able to program the key successfully. I was able to lock the car with the new battery, but was not able to unlock it. The locking mechanism worked (with new battery) for two-three times and then it stopped again.

I joined Bimmerfest just now to say: Thank you! I haven't tried this yet, but need to and really appreciate your taking the time to share your battery replacement experience! I'll see if I can contribute something after I've tackled it. Thanks,

Hello
I have a missing smd piece ( in the red mark ) on my key , i think is a resistor but i'm not sure, if someone have a key opened please read and tell me what are marked on the piece from the picture.
THX in advance.

I broke my key yesterday. When opened I cutted a resistor and cap of the PCB. I have found the cap back and will solder it in place but I lost the resistor. Does someone know what value the resistor is.

Thank you for the fast feedback, i will put the piece back and see if it's working anymore.

If you wanna see pictures of diamond fobs with missing components I got a bunch of them on my key fob wall of shame web page www.bmwgm5.com/KF_WoS.htm
I see key fobs with components whacked off all the time.

Need a advice from the experts,
I've replaced the battery in my key fob with the energizer 2025 while I'm looking for a vendor that will ship the lithium OEM panasonic battery to Hawaii.
All went well, I reeinitiliazed the key and everything works except when I lock the car with the key fob, door locks activate but there is no audible chirp from the horn when doors are locking and the turn signals are not flashing either.

My car used to chirp the horn and flash the blinkers before when the remote was working, I've tried to manually lock the car by turning the key via the door lock and same thing happens, door locks actuate and lock the car, but there is no chirp from the horn or the blink from blinkers.

Be advised that I've only replaced the battery and reinitialized on one dead key fob, the other dead key fob was not touched.
What would case my car to arm it's alarm?
Thanks!

Just for the record, I took the pictures & information from this thread and put them in this diagram, so that others benefit:
For the record, I just made a composite photo of the stock battery (90° offset) and the typical replacement (180° offset).

See also:
- How to replace the old-style BMW E39 square key battery (1) (2) & how to replace the rubber key pads in the old style square keys (1) (2) & where to send your bmw diamond key for repair (1) (2) & what battery to use in the diamond key (1) (2) (3) (4) (5) (6) (7) & square key to diamond key makeover and transponder retrofit (1) (2) & how to recharge your key out of your BMW and how long a BMW key will last in the drawer before it needs that off-the-car recharging (1) & converting the old-style square key to the newer diamond shaped key (1) & the details on swapping the BMW diamond key transponder (1) & proper diamond key initializing (1) (2) & what to do if your key is locked inside your bimmer (1) & a description of the various types of BMW Remote, Illuminated, Spare/Wallet, & Valet/Service keys (1) (2) & a list of diamond key EWS, FZV, & DWA functions (1) (2) & all about the 10-key limit to programming your own keys at home (1) & a description of the ignition key ISN (individual serial number) ten-second rule (1) & what to do if you lost your only diamond key (1) or what to do if your BMW key was stolen (1)